Viability of a Five-Strain Mixture of Listeria monocytogenes in Vacuum-Sealed Packages of Frankfurters, Commercially Prepared with and without 2.0 or 3.0% Added Potassium Lactate, during Extended Storage at 4 and 10° C†‡

The viability of Listeria monocytogenes was monitored on frankfurters containing added potassium lactate that were obtained directly from a commercial manufacturer. Eight links (ca. 56 g each) were transferred aseptically from the original vacuum-sealed bulk packages into nylon-polyethylene bags. Each bag then received a 4-ml portion of a five-strain mixture of the pathogen. Frankfurters containing 2.0 or 3.0% potassium lactate were evaluated using 20 CFU per package, and frankfurters containing 3.0% potassium lactate were evaluated using 500 CFU per package. The packages were vacuum-sealed and stored at 4 or 10°C for up to 90 or 60 days, respectively. During storage at 4°C, pathogen numbers remained at about 1.6 log10 CFU per package over 90 days in packages containing frankfurters with 2.0% potassium lactate that were inoculated with about 20 CFU. In packages containing frankfurters with 3.0% potassium lactate that were inoculated with about 20 CFU and stored at 4°C, pathogen numbers remained at about 1..

DETECÇÃO DE BACTERIOCINAS PRODUZIDAS POR Lactobacillus plantarum BN EM MELAÇO DE CANA-DE-AÇÚCAR SOB FERMENTAÇÃO SUBMERSA

Verificou-se a presença de bacteriocinas produzidas por Lactobacillus plantarum BN (microrganismo teste) em caldo com 3% de melaço de cana-de-açúcar, centrifugado e enriquecido com extrato de leveduras, acetato de sódio e citrato de amônia. Os testes foram realizados em fermentador com volume de trabalho de 3,0 L, sob agitação contínua a 100 rpm, temperatura de 30 ± 0,1°C, aeração de 0,7 vvm, tempo de fermentação de 24 horas e inóculo aproximado de 6,0 Log10 UFC/mL, com tomada de amostras em intervalos de 2 horas. O maior número médio de células viáveis foi de 10 Log10 ciclos logarítmicos, nos intervalos de 12 a 18 horas de fermentação. O pH inicial de 6,49, após 24 horas diminuiu para 5,05. A detecção de bacteriocinas foi realizada no sobrenadante obtido por centrifugação do meio de cultivo, pelo método de difusão em orifícios, usando Lactobacillus sakei ATCC 15521 como microrganismo indicador. Verificouse a presença de bacteriocinas no meio de cultivo a partir de 8 horas de fermentação pela formação de halo inibitório, quando o microrganismo encontrava-se na fase exponencial de crescimento. Comprovou-se a natureza protéica da bacteriocina pelo uso da enzima a-quimotripsina. A bacteriocina produzida por L. plantarum BN apresentou efeito inibitório sobre Listeria monocytogenes ATCC 19112, mas não sobre Staphylococcus aureus ATCC 15489. DETECTION OF BACTERIOCIN PRODUCED BY Lactobacillus plantarum BN IN SUGAR-CANE MOLASSES BY SUBMERSE FERMENTATION Abstract The presence of bacteriocins produced by Lactobacillus plantarum BN (test microorganism) in 3% sugar cane molasses, centrifuged and enriched with yeast extract, sodium acetate and ammonium citrate, was verified. The tests were realized in a fermenter with 3.0 L work volume, under continuous agitation of 100 rpm, at a temperature of 30 ± 0.1 °C, 0.7 vvm aeration and fermentation time of 24 hours with an approximate inoculum of 6.0 Log10 CFU/mL with sample being taken at every 2 hours interval. The greatest number of viable cells observed was 10 Log10 logarithmic cycles at 12 and 18 hours fermentation intervals. Initial pH was 6,49 and after 24 hours, it decreased to 5,05. Bacteriocins detection was accomplished using the supernatant obtained by centrifugation of cultivation media in the well diffusion method using Lactobacillus sakei ATCC 15521 as the indicator microorganism. From 8 hours on of fermentation, presence of colonies surrounded by a clear zone of inhibition indicated bacteriocins production in cultivation media when the microorganism was in the exponential growth phase. The proteic nature of the bacteriocin was certified by using the a-chimotrypsin enzyme. The bacteriocin produced by Lactobacillus plantarum BN presented inhibiting effect over Listeria monocytogenes ATCC 19112 while this effect was not observed in Staphylococcus aureus ATCC 15489

Light fragments production and isospin dependences in Sn+Ni and Sn+Al central collisions at 25MeV/A and 35MeV/A from reverse/isospin experiments

This paper presents the physical analysis results for the following reactions: 124Sn+64Ni, 124Sn+27Al, 124Sn+58Ni at 35MeV/A and 25MeV/A. The main goal of this studies was to find observables sensitive to isospin effects and to present the similarities/differences between the systems characterised by various charge asymmetry factor, defined as I = (NZ)=A. Theoretical simulations based on the Quantum Molecular Dynamics (QMD) model have been performed in order to compare them with the results of the analysis of experimental data. The first phase of the reaction was carried out with the code CHIMERA [1]. The sequential decay of hot fragments was simulated by the code COOLER [2]. The conclusions are as follows: there are observables sensitive to the isospin of the system, such as the Light Charged Particles (LCP) emission and their sensitivity is demonstrated more prominently in the analysis of central collisions at 35MeV/A. The theoretical calculations do not reproduce these relations well

Chromosome evolution in fishes: a new challenging proposal from Neotropical species

We present a database containing cytogenetic data of Neotropical actinopterygian fishes from Venezuela obtained in a single laboratory for the first time. The results of this study include 103 species belonging to 74 genera assigned to 45 families and 17 out of the 40 teleost orders. In the group of marine fishes, the modal diploid number was 2n=48 represented in 60% of the studied species, while in the freshwater fish group the modal diploid complement was 2n=54, represented in 21.21 % of the studied species. The average number of chromosomes and the mean FN were statistically higher in freshwater fish than in marine fish. The degree of diversification and karyotype variation was also higher in freshwater fish in contrast to a more conserved cytogenetic pattern in marine fish. In contrast to the assumption according to which 48 acrocentric chromosomes was basal chromosome number in fish, data here presented show that there is an obvious trend towards the reduction of the diploid number of chromosomes from values near 2n=60 with high number of biarmed chromosomes in more basal species to 2n=48 acrocentric elements in more derived Actinopterygi

Sharing and community curation of mass spectrometry data with Global Natural Products Social Molecular Networking

The potential of the diverse chemistries present in natural products (NP) for biotechnology and medicine remains untapped because NP databases are not searchable with raw data and the NP community has no way to share data other than in published papers. Although mass spectrometry techniques are well-suited to high-throughput characterization of natural products, there is a pressing need for an infrastructure to enable sharing and curation of data. We present Global Natural Products Social molecular networking (GNPS, http://gnps.ucsd.edu), an open-access knowledge base for community wide organization and sharing of raw, processed or identified tandem mass (MS/MS) spectrometry data. In GNPS crowdsourced curation of freely available community-wide reference MS libraries will underpin improved annotations. Data-driven social-networking should facilitate identification of spectra and foster collaborations. We also introduce the concept of ‘living data’ through continuous reanalysis of deposited data

Behavior of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium in teewurst, a raw spreadable sausage

The fate of Listeria monocytogenes, Salmonella Typhimurium, or Escherichia coli O157:H7 were separately monitored both in and on teewurst, a traditional raw and spreadable sausage of Germanic origin. Multi-strain cocktails of each pathogen (ca. 5.0 log CFU/g) were used to separately inoculate teewurst that was subsequently stored at 1.5, 4, 10, and 21 °C. When inoculated into commercially-prepared batter just prior to stuffing, in general, the higher the storage temperature, the greater the lethality. Depending on the storage temperature, pathogen levels in the batter decreased by 2.3 to 3.4, ca. 3.8, and 2.2 to 3.6 log CFU/g for E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, during storage for 30 days. When inoculated onto both the top and bottom faces of sliced commercially-prepared finished product, the results for all four temperatures showed a decrease of 0.9 to 1.4, 1.4 to 1.8, and 2.2 to 3.0 log CFU/g for E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, over the course of 21 days. With the possible exceptions for salt and carbohydrate levels, chemical analyses of teewurst purchased from five commercial manufacturers revealed only subtle differences in proximate composition for this product type. Our data establish that teewurst does not provide a favourable environment for the survival of E. coli O157:H7, S. Typhimurium, or L. monocytogenes inoculated either into or onto the product